Preparation of organosilicon compounds



?atented June 28, 1949 PREPARATION OF ORGANOSILICON COMPOUNDS Ambrose George Taylor, Birmingham, England,

asslgnor to The Dow Corning Corporation, Midland, Mich.

No Drawing. Application July 25, 1947, Serial No.

763,753. In Great Britain February 12, 1946 Section 1, Public Law 690, August 8, 1946 Patent expires February 12, 1966 8 Claims.

1 This invention is for improvements in or relating to the preparation of organosilicon compounds.

It is known that organosilicon compounds can be prepared by the interaction of silicon halides 5 ticularly suitable for use in electrical insulation. with organic magnesium halides by a process in- The compounds which may be used for the provolving the Grignard technique. It is also known duction of these resinous bodies and which can that organosilicon compounds can be prepared by be obtained by the process of this invention are the interaction of organic halides with alkyl those having at least one alkyl group and at least orthosilicates and metallic sodium. two hydrolysable groups e. g., alkoxy or halogen According to the present invention there is groups, directly attached to silicon. Resinous provided a process for the production of alkylbodies are produced from these compounds by a substituted silicon compounds which comprises process comprising hydrolysis by reaction with an reacting a silicon compound containing at least aqueous medium. one alkoxy group directly attached to silicon, with It appears that the mechanism of the reaction a dialkyl sulphate and metallic sodium. The reis the replacement of hydrolysable groups by hyaction may be carried out in the presence or in droxyl groups followed by or simultaneously with the absence of an inert solvent, as desired, and a condensation reaction in which one molecule 01' may be accelerated by the action of heat. water is eliminated from each pair of hydroxyl The silicon compounds which may be used in groups, whereby two silicon atoms become linked the process of this invention may have more than by an oxygen bridge. one alkoxy group directly attached to silicon, and It follows from this that when compounds conin addition may have halogen, alkyl, cycloalkyl, taining three hydrolysable groups are subjected aryl, alkaryl or aralkyl groups also attached dito the resinification process, three dimensional rectly to silicon. Polyalkoxy silanes are particulattices will be formed, whereas if only comlarly suited to the process of the present invenpounds containing two hydrolysable groups are tion, and as examples there may be mentioned used, chain or ring lattices will be formed. It tetramethyl orthosilicate,tetraethyl orthosilicate, will be appreciated that compounds containing dimethoxy dichlorsilane, trimethoxy chlorsilane, only one hydrolysable group will not yield lattices and phenyl trimethoxy silane. when subjected to the resinification process, but The initial products of the reaction comprise it is possible, and often desirable, to use a mixan alkyl-substituted silicon compound together ture containing some molecules having only one with sodium sulphate or sodium alkyl sulphate, hydrolysable group since such molecules, when and sodium alkoxide which would then react with the mixture is hydrolysed, serve to terminate further dialkyl sulphate. This side reaction may c a n growth and thus afford a means of conlargely be avoided by including in the reagents trolling the degree of molecular complexity of or adding to the reaction mixture a silicon comthe resinification products. pound containing atleast one halogen atom at- A mixture of alkyl-substituted silicon comtached to silicon. On reaction with sodium alkpounds resulting from the process of this invenoxide this compound will form sodium halide and- 40 tion may of itself be subjected to the resinificaregenerate an alkoxy-silicon compound. The retion process, or alternatively such a mixture may generated alkoxy-silicon compound can then rebe separated into its constituents by fractiona-. act with further dialkyl sulphate and sodium. tion or other means. These constituent com- As examples of the halogen-containing silicon pounds or suitable mixtures of them may also compounds there may be mentioned silicon tetrabe used to prepare resinous bodies. These may chloride, silicon oxychloride, trimethoxy chlorbe non-viscous liquids, oils, resins or rubber-like silane and methyl chlorsilane. products according to the choice of compound or The alkyl-substituted silicon compounds promixture used. Factors which control the properduced by the process of this invention may be ties of the products are the nature of the alkyl separated from the reaction mixture by distillasubstituent or substituents and the proportions tion whereby the compounds are separated from of compounds containing the various numbers of the sodium compounds remaining in the reaction hydrolysable groups per molecule. mixture. Alternatively, the silicon compounds It is, therefore, in view of the foregoing. a feamay be filtered from the sodium compounds and ture of this invention to react a silicon compound in-either case may be purified by fractionation. having at least one alkoxy group and a total of The most useful products of the process of the for the production of resinous bodies having wellknown and valuable properties making them parsodium chloride.

and/or alkoxy groups per molecule directly attached to silicon, or to yield a mixture of silicon compounds in which at least the majority of mole-- cules each have an alkyl group and a. total of.

at least two halogen and/or alkoxy groups per molecule directly attached to silicon.

which the invention may be carried into effect:

2. The method of preparing alkyl-substituted silicon compounds which comprises reacting molten metallic sodium with a tetraalkylorthosilicate and a dialkyl sulfate in liquid phase, in mixture with a silicon tetrahalide, whereby an alkyl radical from said sulfate is substituted for at least one alkoxy radical of said silicate.

3. The method of preparing alkyl-substituted silicon compounds which comprises reacting molten metallic sodium with a tetraalkylortho- I silicate and a dialkyl sulfate in liquid phase, in The following are examples of various ways in Example 1.23 gms. of metallic sodium were introduced into 250 ml. of toluene and 38 gms.

of tetramethylorthosilicate were added. The mixture was heated under reflux until the SOdillIll-Tz had melted. 76 gms. of diethyl sulphate were then added'slowly with stirring, whereupon a 1 silicone were obtained.

Example 2--23 gms. of metallic sodium were :introduced into 250 ml. of toluene and 19 gms. of

tetramethylorthosilicate were added. The mixture was heated under reflux until the sodium had melted. A mixture of 38 gms. of diethyl sulphate -and 21 gms. of silicon tetrachloride was then added slowly, whereupon a vigorous reaction took place with the separation of sodium sulphate and The liquid phase was distilled away from the sodium salts and the ethyl methroxy silanes which were contained in the distillate 0 were hydrolysed by warming'the toluene solution overnight with 200 ccs. of dilute aqueous hydrochloric acid. Thetoluene layer was separated off and the toluene removed therefrom by distillation. 16 gms. of a liquid ethyl silicone, containing 31.5% by weight of silicon, were ob- .tained.

Example 3.46 gms. of metallic sodium were :introduced into 250 cos. of tetrahydronaphthalene and 38 gms. of tetramethyl orthosilicate. The mixture was heated to 180 C. and a mixture of 63 gms. of dimethyl sulphate, 42 gms. of silicon tetrachloride and 250 ccs. of tetrahydronaphthalene was slowly added. A vigorous reaction occurred with the separation of sodium chloride and sodium sulphate. The methyl methoxy silanes which resulted from the reaction were separated by fractionation from the higher boiling solvent. 40 gms. were obtained containing 24.05% silicon, representing approximately a 70% yield.

I claim:

1. The method of preparing alkyl-substituted silicon compounds which comprises reacting molten metallic sodium with a tetraallcylorthosil- ;icate and a dialkyl sulfate in liquid phase, whereby an alkyl radical from said sulfate is substituted for at least one alkoxy radical of said silicate.

mixture with silicon tetrachloride, whereby an alkyl radical from said sulfate is substituted for at least one alkoxy radical of said silicate.

4. The method of preparing alkyl-substituted silicon compounds which comprises reacting molten metallic sodium, in a liquid aromatic hydrocarbon, boiling above the melting point of sodium, with a tetraallrylorthosilicate and a dialkyl sulfate in liquid phase, whereby an alkyl radical from saidsulfate is substituted for at least one alkoxy radical of said silicate. I

5. The method of preparing alkyl-substltute *silicon compounds which comprises reacting -mo1ten metallic sodium with tetramethylorthosilicate and a dialkyl sulfate in liquid phase, whereby an alkyl radical from said sulfate is substituted for at least one methoxy radical of said silicate.

6. The method of preparing alkyl-substituted silicon compounds which comprises reacting molten metallic sodium with a tetraalkylorthosilicate and dimethyl sulfate in liquid phase, whereby a methyl radical from said sulfate is substituted forat least one alkoxy radical of said .silicate.

7. The method of preparing alkyl-substituted silicon compounds which comprises reacting molten metallic sodium with a tetraalkylorthosilicate and diethyl sulfate in liquid phase, whereby an ethyl radical from said sulfate is substituted for at least one alkoxy radical of said silicate.

8. The method of preparing alkyl-su'bstituted silicon compounds which comprises reacting molten metallic sodium in suspension in toluene, with a tetraalkylorthosilicate and dimethyl sulfate in liquid phase, whereby a methyl radical from said sulfate is substituted for at least one alkoxy radical of said silicate.

. AMBROSE GEORGE TAYLOR.

REFERENCES CITED The following references are of record in the file of this patent:

I UNITED STATES PATENTS Number OTHER REFERENCES Suter et al., Jour. Amer. Chem. 800., vol 55 (1933), page 3496. 

